Powertrain, generic · Hybrid propulsion

P0CEC Hybrid/EV Electronics Coolant Pump A Control Circuit High

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P0CEC flags a pump control line that is held too high, normally a short to battery voltage on the output. GM's HPC2 tables of 2016 and 2019 (16OBDG02, 19OBDG02) look for it while the pump enable is on and the commanded duty cycle is between 0 and 10 %: a line reading high when it should be nearly off counts as a failure, and 16 of 20 samples at 250 ms set the code, Type B, two trips, with system voltage above 10.2 V. A pump with a line pinned high may run constantly or ignore speed requests, depending on its electronics. Open circuits belong to P0CE9, a line pulled low to P0CEB, the separate enable wire to P0CED. The fix is usually in the harness: a pinched wire touching a feed or moisture in a connector.

Likely causes

Control wire shorted to a 12 V feed in the harness
Moisture or corrosion in the pump connector linking supply and control pins
Pump electronics feeding voltage back onto the control line
Output stage in the control module stuck high

Symptoms

  • Malfunction indicator lamp on
  • Pump runs permanently or does not respond to speed changes
  • Possible power limitation of the hybrid system

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€50–650
Time0.5–3 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

hybrid electronics coolant pump awiring harnesshybrid control module

Related codes

P0CE9P0CEBP0CEDP2E44

References: gsi.ext.gm.com, gsi.ext.gm.com, law.cornell.edu.